Surgical staplers have been used in the prior art to simultaneously make a longitudinal incision in tissue and apply lines of staples on opposing sides of the incision. Such instruments commonly include a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members receives a staple cartridge having at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. The instrument includes a plurality of reciprocating wedges which, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil.
An example of a surgical stapler suitable for endoscopic applications, described in U.S. Pat. No. 5,465,895, advantageously provides distinct closing and firing actions. Thereby, a clinician is able to close the jaw members upon tissue to position the tissue prior to firing. Once the clinician has determined that the jaw members are properly gripping tissue, the clinician can then fire the surgical stapler, thereby severing and stapling the tissue. The simultaneous severing and stapling avoids complications that may arise when performing such actions sequentially with different surgical tools that respectively only sever or staple.
These minimally invasive surgical instruments have been widely used and have proven to be a significant advancement over traditional open surgical techniques. It would be desirable to incorporate yet additional features and capabilities. For instance, in Int'l Pat. Appln. WO 03/094743 A1, a wound closure material applicator assembly is described that dispenses at a needle in a knife of a surgical stapling apparatus as the knife is moved to sever tissue. Dispensing is actuated by reservoir compressed by the firing handle or by a separate syringe.
While such an ability to apply a medical substance upon tissue simultaneously with severing and stapling may be desirable, it is believed that it would be desirable to not impose a greater force to fire requirement upon the surgeon, or to require another detached device be actuated.
Consequently, a significant need exists for a surgical instrument with an improved ability to dispense a medical substance.